The present invention relates to liquid applicators and more particularly to a system and technique for applying a controlled coating of liquid to a continuous sheet of material.
In applying a continuous coating of a liquid, such as hot wax, to sheet stock material, such as plain paper or corrugated board, it is economically desirable to optimize usage of the coating liquid. Such optimized usage is generally effected by depositing a minimally sufficient amount of liquid on the sheet stock so as to produce an effective coating. As a result, accurate control of the amount of deposits is an essential requirement of liquid applicators, especially hot wax applicators.
Existing liquid applicators have been reasonably successful in depositing continuous coatings of the liquid to the surface of substantially flat sheet material. However, such liquid applicators have not been entirely satisfactory in transferring controlled amounts of the liquid to the surface of the material so that accurate layers of the coating are consistently deposited. Furthermore, current liquid wax applicating systems have not been able to deposit uniform coatings of relatively low viscosity liquid wax except at very slow feed rates of 60 feet per minute or less.